Mineralogy and CrystallographySource: The American Naturalist, Vol. 30, No. 357 (Sep., 1896), pp. 737-741Published by: The University of Chicago Press for The American Society of NaturalistsStable URL: http://www.jstor.org/stable/2453202 .

Accessed: 21/05/2014 17:38

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org.

.

The University of Chicago Press and The American Society of Naturalists are collaborating with JSTOR todigitize, preserve and extend access to The American Naturalist.

http://www.jstor.org

This content downloaded from 195.78.109.54 on Wed, 21 May 2014 17:38:21 PMAll use subject to JSTOR Terms and Conditions

1896.] Mineralogy and Crysfallography. 737

General Note0.

MINERALOGY AND CRYSTALLOGRAPHY.1

The Chemical Composition of Turquoises.-Carnot2 notes the occurrence of turquoise in the Burrow Mts., Grant Co., N. M., in a sort of pinkish-gray pegmatite. The structure is micro-crystalline, the fracture irregular and somewhat conchoidal. The analysis given is: P205 28.29, Al203 34.32, CuO 7.41, FeO .91, MnO trace, CaO 7.93, MgO trace, H20 18.24, F trace, quartz or clay 2.73, total 99.83. An analysis of the well known Persian turquoise gave P205 29.43, A1203 42.17, CuIO 5.10, FeO 4.50, H20 18.59, quartz or clay .21, total, 100.00.

These analyses and others already published show, it is true, a good deal of variation in the composition of turquoise, yet are thought by Carnot to agree fairly with the formula P205 (Al2 CU3 Fe3 Ca3) 03+ A1203+5 H20. Stress is laid on the determination of all the iron as ferrous. The above data were obtained from, the true oriental tUr- quoise, or that " of the old rock."

The occidental turquoise, or that " of the new rock " may better be called odontolite, coming from the teeth of fossil mammals. They are very variable in composition, and contain iron in the ferric condition, as well as 3.02 per cent, or, in another specimen, 3.45 per cent of fluor- ine, thus differing from the oriental turqquoise.

The occidental turquoise may be distinguished from ordinary bones and fossils by lack of calcium carbonate, presence of feiric phosphate, and by the large quantity of aluminium phosphate, also by the blUe color.

Alstonite and Barytocalcite.-A posthumous note by Mallalrd3 presented to the French Society of Mineralogy by M. Termier, gives interesting comparisons between the properties of the minerals contain- ing barium and calcium carbonates. While barytocalcite has been long considered to be a double salt, the usual view concerning alstonite has been that it is an isomorphous mixture of the two carbonates. A series of analyses made by Chatelier suggests that alstonite may be also a double salt with the same formula as barytocalcite. The prismatic

1 Edited by A. C. Gill, Cornell University, Ithaca, N. Y. 2 Bull. Soc. Fr. Min., XVIII, pp. 119-123, 1895. 3 Bull. Soc. Fr. Min., XVIII, pp. 7-12, 1895.

This content downloaded from 195.78.109.54 on Wed, 21 May 2014 17:38:21 PMAll use subject to JSTOR Terms and Conditions

738 The American Naturalist. [September,

angle of alstonite is determined as 1190 9', which is not in accord with the view that it is an isomorphous mixture of witherite and aragonite, since their corresponding angles are 1170 48' and 1160 16' respectively.

The indices of refraction of witberite, alstonite and barytocalcite for sodium light were measured and compared with those af aragonite and calcite. In the following table, column III gives the mean between the values for aragonite and for witherite:

I II III* IV V VI Aragonite Witherite Mean Alstonite Barytocalcite Calcite

gt 1.5301 1.529 1.5295 1.525 1.525 1.48625 id l1.6816 1.676 1.67Q 11673 1.684 r 1.6859 1.677 1.681 1 (?) 1.686 1.6585 Sp. G. 2.94 4.28 3.61 3.71 3.65 2.73

Attention is called to the remarkable crystallographic similarity be- tween barytocalcite and calcite, notwithstanding the difference in crys- tal system. The cleavage of barytocalcite form a pseudorhomboliedron, being basal and prismatic. The angle of the prism 1060 54', and the angle between the base and prism is 1020 54', while the cleavage rhom- bohedron of calcite has angle of 1050 5'. Moreover, the optical angle of barytocalcite is small, and the negative acute bisectrix make an an- gle of +640 22' with the c axis (i. e., with the intersection of the pris- matic cleavages); the optical angle of calcite is zero, and the negative optical axis makes an angle of + 630 44' with the intersection of two rhombobedral cleavages.

In conclusion Buchrucker's values for the indices of strontianite are corrected. Mallard's values for Na light are: a; 1.518,1 1.664,

r=1.665. Rutile, Cassiterite and Zircon.-According to Traube,4 who

discusses the question of the isomorphism of the above minerals, the etched figures produced by KF or KF HF are exactly similar for each of the three species, and indicate holohedral symmetry in the tetragonal system.

An attempt to make rutile containing SiO2 was not successful, though Traube considers that it must have been so in case rutile and zircon were isomorphous. Synthetic experiments were also made for the purpose of throwing light on the mode of occurrence of Fe2O, in these minerals. By heating chemically pure amorphous titanium diox- ide in a platinum crucible with sodium tungstate and a metallic oxide, the following results were obtained. With Fe2,O rutile was formed containing in one case as much as 5.4 per cent of that oxide; rutile

4 Neues Jahrb. B.B. X, pp. 470-476, 1896.

This content downloaded from 195.78.109.54 on Wed, 21 May 2014 17:38:21 PMAll use subject to JSTOR Terms and Conditions

1896.] 2dineralogy and Crystallography. 739

with 3.01 per cent Mn2O3, and in another case with 1.91 per cent Cr203 was prepared, but similar experiments with the oxides of nickel and cobalt were not successful, the rutile crystals containing no appreciable trace of Ni or Co. Chromiferous crystals of cassiterite were also formed. It seems, therefore, that these substances have a peculiar affinity for the oxides of the type R203, but not for those of the form RO.

Colored specimens of all three minerals become permanently lighter in color on heating.

Marignac's process for fusing zircon (i.e., with KF or with KF HF) was tried with rutile and cassiterite. Like zircon they both fuse rather readily, forming K2 TiP6 and K2 SnF6 respectively.

Miscellaneous Notes.-Wiulfing5 describes a simple apparatus for obtaining monochromatic light from direct sunlight. The experi- ments on quartz seem to show that the apparatus works with a good degree of accuracy. Measurements of the index of refraction of dia- mond gave for A, n=2.4024; for D, n=2.4175; and for H, n_2.4652. These are three of several values determined. The specific gravity of these diamonds referred to water at 40 was found to be 2.522?.003. Hematite from Elba was also investigated, giving:

to C

2.904 2.690 for line A 2.988 2.755 for line B 3.042 2.797 for line C

The specific gravity at 40 is 5.285?t.002. A description is also given of a spectrum apparatus for use with a microscope or an axial angle instrument. In a later note6 Wfilfing gives a table comparing the values of the indices of refraction of the diamond obtained by himself with those determined by Walter; the agreement is very close. He states that either apparatus above mentioned may be obtained of Eug. Albrecht in Tiibingen.

Kretschmer7 describes the occurrence of garnet, vesuvianite, wolla- stonite, epidote, augite, quartz and calcite at the contact of marble with granite near Friedeberg in Silesia. Minute details as to locality, asso- ciation and crystal form are recorded.

Goguel8 reports on the crystal form, and in some cases on the opti- cal behavior of formopyrine, C12 H14 N202, and its addition salts with

5 Tschelrm. Mitth., XV, pp. 47-76, 1895. 6 Ibid, p. 350. 7Tscherm. Mitth., XV, ppI 9-28, 1895. 8Bull. Soc. Fr. Min., XVIII, pp. 27-31, 1895.

This content downloaded from 195.78.109.54 on Wed, 21 May 2014 17:38:21 PMAll use subject to JSTOR Terms and Conditions

74( The American Naturalist. [September,

hydrochloric, sulphuric, nitric, phosphoric and oxalic acids.-Duparc and Pearce9 have measured the crystal angles and observed the optical properties of eight new chemical compounds. These are benzoyl-malic acid, sodium orthophenyl-benzoate, potassium orthophenyl-benzoate, ammon ium phenyl-glycolate, dextrocinchonime phenyl-glycolate, ben- zylic ether of bromo-tolu-quinone oxime, potassium luteo-phospbomo- lybdate and a potassium luteo-phosphotungstate.

Of late numerous additions have been made to our knowledge of the crystallographic and optical constants of organic compounds. The following three papers in Volume XXV in the Zeitscbrift fur Krystal- lographie may be cited as important contributions to this line. 1. The Crystal form of Some New Halogen Derivatives of Camphor, by F. S. Skipping and W. J. Pope; 2. On the Crystal Form of Some Organic Compounds, by W. J. Pope; 3. Crystallographic and Optical Investi- gations on Some Organic Compounds, by E. A. Wfilfing.

An artificial cassiterite investigated by Arzrunil? shows distinct dichroism with the ray vibrating parallel to the vertical axis colorless, while the ray vibrating at right angles thereto is pink. The crystals reach a half centimeter in thickness and twice that in length. Twins, which are so common with natural cassiterite, were not observed. The angles measured coincide within 2' with those given by Becke for the natural mineral. The mean values from two determinations of the in- dices of refraction are:

Li Na Tl w 1.9846 1.9968 2.0093

2.0817 2.0929 2.1053 These numbers agree as well as could be expected with those ob-

tained by Grubenmann for cassiterite, showing that the natural and artificial products are practically identical.

Schmidt' gives at great length tables showing the recurrence of like interfacial angles in the regular system. As an extreme example, the angle 350 15' 52" occurs between eleven pairs of faces, the cube, octa- hedron or dodecahedron constituting one face of each pair. Thetable at the end of the paper may be of use for rapidly identifying rare faces on regular crystals.

Sohncke'2 shows that in accordance with his views of crystal structure no circular polarization is to be expected in crystals of the pyramidal

9 Bull. Soc. Fr. Min., XVIII, pp. 31--43, 1895. ?0Zeitschr. f. Kryst., XXV, pp. 467--470, 1895. "Zeitschr. f. Kryst., XXV, pp. 477--503,1895. 12 Zeitschr. f. Kryst., XXV, p. 529, 1895.

This content downloaded from 195.78.109.54 on Wed, 21 May 2014 17:38:21 PMAll use subject to JSTOR Terms and Conditions

1896.1 Petrography. 741

tetragonlal class (hemimorphic hemihedral division of the tetragonal system). So far as known, circular polarization is not exhibited by crystals with this grade of symmetry.

PETROGRAPHY.1

Petrography of the Bearpaw Mountains, Montana.-The Bearpaw Mountains are the dissected remains of a group of Tertiary volcanoes. Their cores of the old volcanoes are granular rocks, their lavas and tuffs are represented by basic sheets and beds. The lavas are largely basalts, leucite-basalt and other similar basic types.2

The cores consist of mica-trachytes, quartz-syenite, porphyries, con- taining aegerite-augite and aniothoclase-phenocrysts, in which are im- bedded microlites of oligoclase, trachytes containing hornblende and diopside and shonkinite. A few miles from Bearpaw Peak a denuded core is exposed, which furnishes a good example of the differentiation of a syenite in place. The intrusion is laccolitic in character. Around its borders it has highly altered the sedimentary rocks with which it is in contact. The most acid portion of the laccolite is a light aplitic syenite containing quartz and diopside. The main mass is a more basic syenite resembling monzonite or yogoite. It contains diopside and much plagioclase. The most basic phase is a shonkinite. Analyses for the three principal types follow:

SiO2 A1203 Fe203 FeO MgO CaO Na)O KO H0205 Other Total Quartz-syenite 68.34 15.32 1.90 .84 .54 .92 5.45 5.62 .45 .57 - 99.95 Monzonite 52.81 15.66 3.06 4.76 4.99 7.57 3.60 4.84 1.09 1.86 =100.24 Shonkinite 50.00 9.87 3.46 5.01 11.92 8.31 2.41 5.02 1.33 2.68 =100.01

The totals corrected for Fe and Ce are 99.94, 100.22 and 99.93 respec- tively.

Two French Rocks.-In the serpentine of St. Pr6jet-Armadon, Hauite-Loire, France, Lacrou3 finds nodules composed of asbestiform gedrite surrounding a kernel of serpentine or biotite. The nodules are separated from the serpentine by an envelope of biotite. They are sup-

' Edited by Dr. W. S. Bayley, Colby University, Waterville, Me. 2Weed and Pirson: Amer. Journ. Sci., IV, Vol. 1, p. 283 and 351. 3Bull. Soc. Franc. d. Min., XIX, p. 687.

This content downloaded from 195.78.109.54 on Wed, 21 May 2014 17:38:21 PMAll use subject to JSTOR Terms and Conditions